This invention relates to a pan unstacking and stacking system, and more particularly to a pan handling system intended primarily for use in conjunction with bread pans and other pans of the type commonly employed in the baking industry.
In the operation of a modern automated bakery, it is frequently necessary to move a large number of a particular type of baking pan onto or off of the baking line. For example, a particular size and/or type of pan may be associated with a particular type of bread. Whenever it is desired to bake this type of bread, a quantity of baking pans sufficient to accommodate the contemplated baking run must be moved onto the baking line in order to receive the baking dough and transport the dough through the baking oven. Subsequently these pans must be removed from the baking line in order to make way for the baking pans required by the next baking operation.
While the function of moving baking pans onto and off of a baking line may obviously be performed manually, apparatus known as pan unstackers and stackers has heretofore been provided for performing this function. Thus, baking pans not required for a particular baking operation are typically accumulated in stacks and transferred to a storage area. Whenever the pans are required for a baking operation, the stacks are moved from the storage area to the pan unstacker which functions to transfer individual pans from the stack onto the baking line. Subsequently the pan stacker removes individual pans from the baking line and accumulates the pans in stacks which are later transferred to the storage area. It will be understood that in certain instances the pan unstacker and stacker apparatus may comprise the same machine which is simply operated in reverse directions.
Although various pan stacking and unstacking systems have been provided heretofore, a number of problems have generally remained unsolved in the industry. One such problem involves reliability of operation. Thus, since the unstacking and stacking system may comprise the only means available for moving pans onto and off of a baking line, a failure of the unstacking and stacking system can necessitate the shutdown of an entire automated baking facility. This can be extremely costly, not only from the standpoint of down time, but also from the standpoint of the potential loss of baking dough and other perishable materials.
Another problem which has heretofore not been completely solved in the design of pan unstacking and stacking systems for the baking industry involves the ability of such systems to handle pans of various sizes. Thus, in order to be commercially acceptable, such a system must be capable of unstacking and stacking all the various sizes of baking pans which are utilized in the associated baking system. Of equal importance is the requirement that the adjustments necessary to accommodate the system to different sizes of pans be carried out reliably and without difficulty so as to minimize the time required to effect conversion from one pan size to another.
The present invention comprises a baking pan unstacking and stacking system which fulfills the foregoing requirements while simultaneously eliminating difficulties that have long since characterized the prior art. In accordance with the broader aspects of the invention, opposed pairs of pan engaging members are mounted on opposed pairs of spaced, parallel lift chains and function to vertically position stacks of pans by engagement with the lowermost pan of the stack. The lift chains are driven by drive shafts having drive sprockets which engage the upper and lower chain courses of the drive chain. This permits varying the spaces between the pan engaging members to accommodate baking pans of various sizes without disturbing the vertical positioning of the pan engaging members relative to one another.
The drive chain is in turn driven by a pneumatic cylinder operating through a power input chain, a power input sprocket, a clutch and brake apparatus, a power input shaft and a drive sprocket mounted on the power input shaft and engaging the drive chain. The power input chain is connected at one end to the rod of the pneumatic cylinder and at the other end to a smaller pneumatic cylinder functioning to maintain a predetermined tension on the power input chain. The use of pneumatic cylinders to supply the power for vertically positioning the pan stacks is advantageous in that any jam or other system malfunction simply results in stalling the system rather than in a burnout, as is often the case when an electrical prime mover is used. Moreover, the system is economical in that no power is utilized except during the actual vertical movement of the pan stacks.
The pan unstacking and stacking system further comprises a pan transporting apparatus for effecting lateral pan movement. A plurality of magnets extend along a line positioned in a horizontal plane above the pan stacks. V-belt power transmission belts are mounted for rotation in vertical planes extending adjacent the line of magnets. Each belt rotates around a course including a portion extending coincident with the horizontal plane of the magnets. The belts therefore function to effect lateral movement of pans supported by the magnetic field of the magnets. In the unstacking portion of the system, certain of the magnets are initially moved downward, whereby the uppermost pan is removed from the stack by the magnetic field of the magnets. The magnets are then moved upwardly to engage the pan with the moving belts, whereby the pan is moved laterally. In the stacking portion of the system the belts position a pan above the stack, whereby the pan is moved downwardly out of the magnetic field and is dropped onto the top of the stack.